1. Warm Up  How do you find an element’s valence electrons?  How many valance electrons does an atom need to be stable?

2. Vocabulary  Electron dot diagram  Ion  Anion  Cation  Chemical bond  Ionic bond  Chemical formula  Crystals

3. Chapter 6 - Compounds Formed by 2 elements in a fixed proportion There are only 3 possible combinations Metal + Nonmetal = IONIC Compound Nonmetal + Nonmetal = COVALENT Compound Metal + Metal = METALLIC Compound

4. Why Bind?  Stable Electron Configuration An atom is stable when the outer energy level is full (8 electrons or 0) Octet Rule-states that elements gain or lose electrons to attain an electron configuration of the nearest noble gas.

5. Formation of Ions Ions are ATOMS WITH A CHARGE When an atom gains or loses an electron, its number of protons no longer equals the number of electrons. An atom with a positive or negative charge is an ion Atoms that lose electrons become positive. Positive ions are called cations. Atoms that gain electrons become negative. Negative ions are called anions

6.  When anion and cation are close a chemical bond forms. A chemical bond is the force that holds atoms or ions together.  Ionic bond is the force holding cations and anions together

7. Ionic Compounds In ionic compounds electrons are TRANSFERRED Positive and negative charges attract When cations and anions are close together they form a bond through the transfer of electrons Ionic Compounds= metal plus a nonmetal

8. Ionization Energy  When atom absorbs energy the electron can move to a higher energy level.  Cations form when electrons gain energy to escape from atoms.  The amount of energy used to remove an electron is called ionization energy.

9.  The lower the ionization energy the easier to remove an electron.  Ionization energies tend to increase from left to right across the periodic table. More energy required to remove electrons from a nonmetal than a metal in the same period.  Ionization energies decrease from top of a group to the bottom.

10. Charges Among Groups Ions formed by elements in the same group have the same charge Metals are Always POSITIVE (cations) NON-metals are always negative (anions)

11. A. Ionic Bond  Attraction between 2 oppositely charged ions Ions - charged atoms formed by transferring e - from a metal to a nonmetal

12. Properties of Ionic Compounds  High melting point/boiling point  Poor conductor of electricity/good insulators  Crystals shatter when struck  Melted-good conductor of electricity  When dissolved in water to form an aqueous solution ionic compounds conduct electricity.  Hard.  Brittle

13. Chemical formula  Shows elements in compound and the ratio of atoms or ions in the compound.

14. Naming Ionic Compounds  NaCl –Name of the cation goes First Sodium –Name of the anion goes second Replace the last syllable with –ide Chloride –Put them together Sodium chloride  AlP  MgF  LiO 2

15. Combining Elements to form Compounds  What is the compound formula formed between lithium and fluorine Write symbols Write charges Cross charges, (bring them to bottom) Re-write

16.  http://www.learner.org/interactives/peri odic/groups_interactive.html http://www.learner.org/interactives/peri odic/groups_interactive.html

17. Review  1. When is an atom least likely to react?  2. Describe one way an element can achieve a table electron configuration.  3. What characteristic of ionic bonds can be used to explain the properties of ionic compounds